IDEA: Adds a Tracker plugin

["Juan A. Suarez Romero" <jasuarez igalia com>]

Becoming Tracker a de-facto service in Meego and also Gnome, having a
pluging providing multimedia content based on tags would be great.

We would use the tags to create a hierarchy to browse, as "All authors",
"All genres", "Author > Album", and so forth.

Also, we could implement the query function by using directly sparql as
the query language; thus, the query would be directly forward to
Tracker.

	J.A.